"Hermione's hair was bushy again; she confessed to Harry that she had used liberal amounts of Sleekeazy's Hair Potion on it for the ball, 'but it's way too much bother to do every day,' she said matter-of-factly, scratching a purring Crookshanks behind the ears."

Sleekeazy's Hair Potion and Scalp Treatment was a hair care potion and scalp treatment that was presumably invented by Sleekeazy.[1][2] Noted as being suitable for all hair types on its label,[1] it was particularly effective at taming bushy, unruly hair, allowing it to be styled "sleek."[2] However, the label apparently cautioned against use of the product by redheads, stating it would have "unique results" for them.[1]